Sweat was evaluated as a media for use in monitoring drug exposure of human subjects. Healthy subjects with a history of chemical substance abuse volunteered for these studies. Informed consent was obtained and all procedures were approved by the hospital Institutional Review Board. Following the administration of cocaine, marijuana or opiates, sweat samples were collected periodically. Other biological specimens like saliva, blood, urine and hair also were collected. Specimens were analyzed by immunoassay and gas chromatography/mass spectrometry. These data will provide new information on this unusual biological specimen which may be useful in development of methods for monitoring human drug exposure.